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Electrochemical study of the π* probe dye 5‐nitro‐5′‐dimethylamino‐2,2′‐bisthiophene
Author(s) -
Norambuena Ester,
Rezende Marcos Caroli
Publication year - 1998
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199806)11:6<419::aid-poc14>3.0.co;2-k
Subject(s) - chemistry , solvatochromism , nitro , radical , photochemistry , electron paramagnetic resonance , acceptor , ring (chemistry) , electrochemistry , radical ion , ion , organic chemistry , molecule , electrode , nuclear magnetic resonance , alkyl , physics , condensed matter physics
Cyclic voltamograms of the solvatochromic dye 5‐nitro‐5′‐dimethylamino‐2,2′‐bisthiophene ( 1 ), introduced recently as a sensitive π* probe, were recorded in different solvents. An EPR spectrum of the anionic radical of 1 in DMSO was obtained and compared with other spectra of analogous substituted bisthiophene radicals. It was found that the presence of a donor– acceptor pair of substituents in 1 −⋅ reduces significantly the rotational barrier of the radical compared with the unsubstituted bithienyl radical anion 2 −⋅ . This is the result of an electronic repulsion between the donor ring fragment and the added electron in the coplanar radical, which does not exist in 2 −⋅ . © 1998 John Wiley & Sons, Ltd.